Communication technology has made considerable progress in recent years. According to one aspect of such progress, communication networks providing access to different services by means of different technologies such as GSM (Global System for Mobile Communications), UMTS (Universal Mobile Telecommunications System), Bluetooth©, WCDMA (Wideband Code Division Multiple Access) and WLAN (Wireless Local Area Network) were developed.
Most recently, communication networks and terminals which are enabled for access to a network enabling access by one out of plural of such technologies are being developed. Such networks and/or terminals are referred to as multi-access networks/terminals. Those multi-access networks allow access to data services via multiple technologies such as GSM, GPRS (General Packet Radio Service), WCDMA, UMTS and the like. These technologies may require the establishment of a PDP (Packet Data Protocol) context between the terminal and the network. Further technologies providing access to data services include technologies such as WLAN, WiMAX (Worldwide Interoperability for Microwave Access), xDSL (Digital Subscriber Line), xPON (Passive Optical Network) and cable modem. These technologies may be used in conjunction with IPsec (IP (Internet Protocol) Security) tunneling in order to provide encrypting and/or authentication functionalities and the like. All these different technologies may require a different kind of access termination functionality, which can be implemented in one or many network elements.
The applicable technologies are, however, not limited to those relying on a PDP context (e.g. GPRS) or IP/IPsec tunneling (e.g. WLAN), but may be based also on other principles.
Functionalities like charging and ensuring Quality of Service (QoS) can quite often be access technology dependent. When seamless service continuity is implemented by adding a mobility layer on top of the access termination layer, there will arise a requirement of conveying the access specific information between the mobility and access termination layer.
For the purpose of the present invention to be described herein below, it should be noted that
an access technology may be any of the above-described technologies by means of which a terminal can access a communication network. Although in the following only GPRS based on the PDP context and WLAN via IP/IPsec are used as exemplary access technologies for descriptive purposes, other present or future technologies, such as the technologies described above or BlueTooth©, Infrared, and the like may be used; although the above technologies are mostly wireless access technologies, e.g. in different radio spectra, access technology in the sense of the present invention may also imply wirebound technologies;
a network element may for example be any device, unit or means by means of which a user may have access to a communication network, or which enables a user to experience services provided by the communication network;
a terminal in turn may for example be any device, unit or means by means of which a user accesses a communication network, i.e. at least one network element thereof; this implies that a terminal as referred to in the present specification may correspond to a mobile as well as a non-mobile device, independent of the technology platform on which the terminal is based; the terminal can be capable of performing multi-access, i.e. can establish a connection to any network element as long as at least one commonly used access technology (e.g. GPRS or WLAN) can be agreed on;
generally, the present invention is advantageously applicable in those network/terminal environments relying on a packet based transmission scheme according to which data are transmitted in packets and which are for example based on the Internet Protocol IP, e.g. mobile IP. In a particular example of the present invention, mobile IPv4 (MIPv4, mobile IP version 4) is applied. The present invention is, however, not limited thereto, and MIPv6 or any other IP version, or, more generally, a mobility protocol following similar principles as MIPv4, is also applicable.
a gateway entity as a network element or at least as a part of a network element may be any device, unit or means by which the terminal can connect to or communicate with the network or network element (while taking into account the at least one commonly used access technology);
an agent entity may be any device, unit or means which registers a terminal to a communication network;
a home agent (abbreviated as “HA” hereinafter) entity may be any device, unit or means which serves as an entry point for the terminal into a network; as a particular example, the home agent entity may be a MIPv4 Home Agent.
method steps likely to be implemented as software code portions and being run using a processor at the network element, are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;
generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention in terms of the functionality implemented;
method steps and/or devices, units or means likely to be implemented as hardware components at a terminal or network element or module thereof are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;
devices, units or means (terminals, network elements or modules thereof) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved.
RFC (request for comments) 4433 describes a method of dynamically selecting a home agent entity by sending the initial registration request to a default home agent entity (HA) called “Requested HA”. While these comments do not address how the actual and finally selected home agent entity should be selected, there is disclosed an example how that could be achieved e.g. by using an external AAA (“Authentication, Authorization and Accounting”) infrastructure. The external AAA infrastructure may cooperate with a server entity providing at least one service to the network and/or the terminal.
FIG. 1 shows a communication system 100 and such messaging involved in registering a terminal 101 at a communication network 102-105, 1021, 1024. Signalling between elements is indicated in horizontal direction, while time aspects between signalling are reflected in the vertical arrangement of the signalling sequence as well as in the sequence numbers.
As shown in FIG. 1, in the communication system 100, the terminal 101 sends a connection-establishment request to a gateway entity GW 1021 of a network element NWE 102 in step S1 so that a connection is established. Generally, connection establishment, among others, involves assigning an address to the terminal which may also be accomplished in other ways than establishing a connection.
In step S2, the gateway entity GW 1021 sends a RADIUS accounting start containing the user ID and user IP address to an external AAA server or system server 104, respectively. Thus, the system server 104 has received, in the message, information about the access termination and can therefore determine the location of the home agent (“HA” hereinafter) entity 1024 considered to be optimum.
In step S3, an initial registration request is sent from the terminal 101 to the external default HA 103.
The external default HA 103 inquires an address of the home agent entity 1024 for the terminal 101 from the system server 104 in step S4, and obtains the address of the home agent entity 1024 from the system server 104 in step S5.
In other words, because the goal can be considered to select HA1 1024 located in the same node or network element NWE 102, respectively, as the access termination and since the external default HA 103 does not know where the access is terminated, it has to ask that information from the system server 104. The system server 104 can then return this information to the default HA 103 in step S5 and the default HA 103 will then use this information to redirect the mobile IP session to HA1 1024, which is considered to be a possible optimum HA.
Namely, the default HA 103 sends in step S6 a redirect message to the terminal 101 containing an address of HA1 1024 considered to be optimum, which is in most cases the agent entity in the same network element NWE 102 in which the terminal 101 is access-terminated.
Based on the home agent entity address received from the default HA 103, the terminal 101 sends a further registration request to the home agent entity 1024 in step S7.
In step S8, having learned the home agent entity 1024 considered to be optimum, the terminal 101 may now access services 105 in the system server 104 via the gateway entity GW 1021 and the home agent entity 1024.
As derivable from FIG. 1 to be explained herein below in more detail, in the above solution, considerable signalling is required for selecting the HA by referring to the system default HA 103 and the system server 104, and for redirection to the HA 1024 in the access-terminating network element NWE 102. However, in many cases the HA to be selected is the agent entity in the same network element NWE 102 in which the terminal is access-terminated. Furthermore, two independent signalling messages (messages sent in steps S2, S4) are sent to the system server 104.
Therefore, the above solution has one or more of the following drawbacks:
It is slow:
The above signalling is performed irrespective of the fact whether or not the HA to be selected is situated in the access-terminating network element.
It pertains the danger of synchronisation problems:
The above two independent signalling messages may arrive in improper order at the system server.
Processing load is put on the system server:
All signalling is directed to the system server irrespective of fact that in many cases inquiring the correct HA from the server is not required.